#include <stdio.h>
int main()
{
	int a=1;
	double x,y,sum;
	x=2.0;
	sum=1.0;
	while(x<=100)
	{
		a=(-1)*a;
		y=a*(1/x);
		sum=sum+y;
		x++; 
	}
	printf("%f\n",sum);
	return 0;
}
